It's an old question, but an important one. Let's see if we can get a good, nuanced, ideally evidence-based answer.

So, old-school wisdom (certainly, how I was taught back in the day) says that serif text improves the readability of long passages of text. The eye passes over the text more easily, there is less "fatigue" on the eye, and reading speed is improved. As I was taught, this is the reason why book typesetters almost always use moderately florid serifs like Garamond. Sans-serifs, according to traditional wisdom, are better for legibility - the letters are simpler, less room for error - and so are better suited for short text, like road signs.

Within the last decade or so - certainly since reading on screens became commonplace - I've seen an increasingly common viewpoint that this is an outdated myth - that actually, serifs are faster for reading long text for no reason other than that we are historically accustomed to reading long passages of serif text, and that long passages of well typeset, well chosen sans can be just as good for readability and fast reading, as people become accustomed to it.

There's also a third viewpoint I'm aware of, which says that the second viewpoint is a myth that comes from the fact that serif fonts tend not to reduce well on pixel screens, making sans type the better (least worst) choice for long passages of on-screen text or poorly-printed reproductions, but serifs still the best for long passages of printed type. Hence the popularity of websites with sans body text and serif headers, and of printed materials with serif body text and sans headers. Essentially, it characterises the arguments for the second viewpoint as merely pointing out that good (well produced) sans type is better than bad serif type, and maintains that, for extended reading, all other things being equal, good serif type is better than good sans type.

And finally, there's a fourth viewpoint that it doesn't matter anyway - that there are no differences between serifs in general and sans in general that are not merely artefacts of the differences between the example fonts and typesetting used in any particular test or comparison. There's certainly a case to be made for this in the context of legibility, but I've not seen anything convincing on this for readability.

All other things being equal, do serifs on a typeface genuinely make lengthy body text easier (faster and less effortful) to read?

Readability (as defined by the speed of error-free reading) is something objective that can be, and has been, measured. This is a factual question. Can we give it a solid, rounded, nuanced factual answer?

A couple of asides relating to common arguments I've seen:

There's an old-fashioned justification for serifs based on the idea that the eye follows a line of text, and the serifs, by hinting at a cohesive horizontal, help the eye along its way. The first part of this is simply not true - the eye moves in numerous extremely fast jumps ('saccades') we are not consciously aware of, and the motion between jumps is too fast for any information to be taken in. It's 'Jump-focus-jump-focus-jump-focus', leading to one awareness of the area covered by the jumps. However, this doesn't completely nullify the gist of the argument. It's perfectly possible, for example, that serifs could help create implied cohesive horizontals in the blurred areas of vision outside the fovea which could help the reading process by guiding saccades and/or making word boundaries more distinct.

A point is sometimes made about serifs being a cultural artefact. That's undoubtedly true - but it's interesting to note that many scripts have optional equivalents to serifs which, like Roman serifs, mark significant protrusions and corners, and which in some cases have a history that can't be put down to simply following popular roman typefaces. For example, they're historically important in Chinese (and therefore also Japanese) writing, and interestingly, give a sense of direction that is both horizontal and vertical (makes sense as historically these have been written in a variety of directions). So, it's not grounds for dismissing serifs as just an artefact of one cultural heritage.

Great question. I suspect it's a myth, but I don't have any evidence to present (I've read tests over the years, but can't remember where). And, if nothing else, readers read best what they read most. A lot of text is sans serif, so I doubt there's any meaningful difference between sans serif and serif. The important differences are probably when comparing typefaces, not serifs.
–
Marc EdwardsOct 1 '12 at 23:44

3

This may also be a good candidate for skeptics.se.
–
berry120Oct 2 '12 at 14:37

1

I agree that this is a little off topic (though interesting). However, it is likely to be a wiki-style with no clear answer and certainly little rigor.
–
horatioOct 2 '12 at 17:38

I can tell you that I personally find it much harder to read, and with large texts, I lose my focus much quicker.. There ARE more strokes than nessecary, after all.
–
poepjeOct 3 '12 at 9:01

I just wonder: Wouldn’t now be the perfect time to perform a scientific study of this? It should be possible now to assemble a test group, that is as familiar with serifs (in print) as with sans-serifs (on screen) or at least very familiar with both. Fonts are at easily available, so one can easily remove the bias by individual fonts by using a selection of the best-readable fonts of each category. You could most probably even crowdfund the whole project.
–
WrzlprmftFeb 6 '14 at 8:41

8 Answers
8

Summed up into a couple of points, here are my thoughts on the subject.

"Readability" is also about what we are most familiar with. English speakers tend to be familiar with both serif and sans-serif typefaces, enough to be able to read both extremely fluently. You could say that most of our most lengthy reading (eg, novels, newspapers) uses traditional/transitional serif faces, so the argument could be made that we ought to be slightly more at ease with these particular serifs. But in actuality, we're very good at reading common sans-serif fonts too, to the point where we're good enough at both for any individual differences to be unsubstantial.

As for people who use other alphabets than our Latin alphabet, this will be different. There are some alphabets/scripts which do not have a serif/sans-serif equivalent or if they do, one is rarely used, in which case the more common one will be the more readable form.

The technical specifics of a low resolution computer screen (ie, not a retina display/high resolution smartphone) have always limited what we can do with type in that medium, and for various reasons sans-serif became the norm there for a long time. The reason for sans-serif being regarded as more "readable" on a low-resolution computer screen is more to do with technical aspects; serif fonts render more poorly at the lowest of resolutions as their small details are lost/squished when fitting to the pixel grid.

Fonts such as Georgia and Droid Serif are notable in that they are specifically designed to be quite well readable even at fairly low resolutions on a screen. But if you consider a serif typeface that works excellently in print, like Caslon or Garamond, these are an atrocious mess at low resolutions on-screen. Whereas in print, I would claim Adobe Caslon to be one of the most readable fonts out there. Probably harking back to point 1 - because it's so familiar to us.

Higher resolution screens (the "retina display" trend) are also lessening the need to worry about fitting type to the pixel grid, putting traditional serifs once more onto an even footing (on such displays).

Serif type pre-dates sans-serif and the serifs are originally imitations of chiseled type in stone which then went on to be used just for aesthetic reasons. It was not like there was both serif and sans-serif and one was "chosen" over the other - it would be hundreds of years later before the first sans-serif appeared, and even then it was scorned a little bit at first. So, obviously, if someone were to claim that serifs were "invented" to ease readability, implying that before that all text was sans-serif, then they're putting the cart before the horse in terms of their understanding of history.

"Serif type pre-dates sans-serif" = not true. The origins of serifs are also not clear. There are lots of theories, and many have become accepted folklore, though.
–
DA01Oct 2 '12 at 16:19

Sans-serif type only emerged in the 19th century, or 18th if you count non-Latin alphabets. Serif types were hundreds of years earlier. Either you are thinking of something other than printed type or you are thinking of something other than sans-serif.
–
thomasrutterOct 3 '12 at 4:01

If you are referring solely to moveable type, you are correct. However you refer to the origins of serifs predating moveable type, as does the origins of sans-serifs. I agree with your statement, in general, though. Merely pointing out that there's a lot of muddy waters when it comes to specifics of type legibility and history in general.
–
DA01Oct 3 '12 at 8:08

English is NOT the best-constructed language. It's a mess of etymological influences, irregular verb conjugation, homonyms, and there are just exceptions everywhere. I'm sure people could successfully make the case that Spanish or Esperanto or whatever is not only a better candidate for lingua franca status because of the ability to learn it quickly and perhaps it could be more descriptive in nature.

But at the end of the day, winning that argument and printing a piece in Esperanto doesn't mean a thing if your audience is a group of Americans. I've heard before that "we read best what we know best," and I think that's true of typography. I bet more than a few Germans were uncomfortable with serifs when they first came out, having been familiar with reading blackletter.

There are a lot of things that improve readability (leading, kerning, stroke contrast, type contrast to page background, weight, margin size, column width) without even getting into the serif/sans serif debate. The debate has the most merit on screen, where I think that limited resolutions have favored sans-serif for technical reasons.

I welcome the debate, but when I choose between the two it's typically based on whether I want a traditional or modern "feel," and whether or not the target audience would be familiar (though I think that with the popularity of sans serif on the screen and serif in print evens this argument out, particularly among the younger demographic).

Couldn't agree more that there are more important differences within serifs and sans than between the two groups, which is why I particularly say all other things being equal. But if there is a difference, it'd be useful to know about, not least because the underlying principles for any such a difference would likely have other applications. And if there isn't, there's an interesting followup question of what other reason causes serif-like ticks to be apparently so popular throughout so much of history and in numerous cultures.
–
user568458Oct 2 '12 at 16:41

1

As a sidenote: There are still some fanatics who claim that blackletter has superior legibility for the German language and argue that it should be reintroduced for that reason.
–
WrzlprmftFeb 6 '14 at 7:56

@Wrzlprmft - Very interesting! Any relevant links? I'd be interested in reading more (even if it is through a translation service).
–
BrendanFeb 6 '14 at 14:02

This one gets pretty deep into the real mechanics of the issue. In a response to multiple preceding discussions, Peter Enneson starts off an intellectual's debate on the issue.

In perceptual processing terms I see the reader's ability as primarily
twofold. 1) an ability to see many (even eccentric) varieties of a
letter as a given letter (for example a Raffia A as an a); 2) an
ability to visually integrate ensembles of orthographically regular
clusters of stimulus units (letters on a page) into familiar,
object-like, perceptually molar, sense units. Both involve perceptual
learning, and the second ability is underdeveloped in people with
dislexia.

A short discussion between two important members from the early days of Typophile (the golden years, if you will). It centers on the coining of the word 'bouma' to describe word shapes and their place in reading mechanics/perception. It's definitely academic but there are some great takeaways on the micro-considerations of type design and selection.

Nice, though we don't normally like answers that are mostly links as they become useless if (heaven forbid) Typophile was ever to go down or delete or move its old content. Any chance of a one-line summary of the key point of each one? That would also give this answer an answer-like overall message.
–
user568458Oct 4 '12 at 0:31

The wall of links scared me. Full support to the first comment.
–
Nikana ReklawyksNov 12 '12 at 9:13

Sorry folks. These are long-winded discussions. If I could summarize, Typophile could change to a blog format ;) Enjoy them while they last. If I get a chance, I'll come back and at least title them.
–
plainclothesNov 12 '12 at 17:36

Studies of readability and legibility are few and far between and mostly inconclusive in deciding broad questions like this.

The only consistent result is that people tend to read best what they read most.

The big catch is that 'all things being equal' is really hard to study. There are very few typefaces one could call 'being equal' aside from having a sans vs. serif version and even of those, one is really testing the legibility of that particular face rather than the serifs themselves.

I think we like to think of typography as being a purely scientific field of study but it's mostly art. ;)

I think your point is crucial: any test (and discussion) needs to be about a pair of fonts made for the express purpose of testing readability and which differ only in serifs. Anything else is just hand waving really.
–
horatioOct 2 '12 at 17:32

I notice it myself, if there isn't enough line spacing, then I can read serif faster. I respond to the visual hints.

Related, which might shed evidence on the subject, is the publication of fonts directed at dyslexics, which use weight in the letters to further hint at their form. To me that says that extra visual information is processed and can increase readability.

I don't think one can make the leap that serifs offer the same benefits to people as custom fonts for dyslexia offer to dyslexics.
–
DA01Oct 2 '12 at 16:16

2

The original poster asked if serifs increased readability. My point is that since dyslexic fonts use visual cues and weight to assist dyslexics (successfully, one would assume), then there is a case for subtle visual cues improving readability, and I don't see it as a great leap to assume that serifs would perform a similar function.
–
Stephen O'FlynnOct 2 '12 at 16:21

I do understand your point. It sounds like a valid theory, but an untested one.
–
DA01Oct 2 '12 at 16:22

1

Bringing in findings from dyslexic research is definitely welcome, not least because the quality of research seems stronger (it being a well established research area with strong foundations). Arguments well reasoned from base principles and areas of basic research are definitely welcome whether or not a branch of more applied research happens to have got in on the act.
–
user568458Oct 2 '12 at 16:46

2

It's just a theory (my conjecture). I brought it in because I thought it might provide another avenue of investigation.
–
Stephen O'FlynnOct 2 '12 at 17:30

My two cents, I really like this article on kadavy.net. It says, basically, serifs on paper and sans-serif on screens. Serifs might look muddled on screens with low DPI counts, because of the pixel raster. Because of this reason it is also better to use letters with a high x-height on screens.

Personally, I like the distinction for paper and computer screens, but that could be because I'm so used to it.

I find it interesting that the "serif vs sans-serif" wars ignore a trait which commonly goes along with serifs: variable stroke widths. Variable stroke widths can improve readability even at bitmap resolutions which are too small to show serifs cleanly; I generally find serif fonts which have fixed stroke widths inferior to sans-serif fonts with variable stroke widths, regardless of the size or medium. I suspect much of the "advantage" of serifs comes from the fact that most serif fonts use variable-width strokes and most sans-serif fonts do not.
–
supercatJul 28 '14 at 18:30

The "studies" on Serif v Sans Serif ignore the most important mass of evidence that serifed faces are FAR superior in printed applications.

Mail order advertisers constantly track different aspects of advertisements and are able to do exact "split run" testing for millions of copies of newspapers or magazines. Mailorder ads have traditionally been very heavy on text and the text contains the sales pitch leading to purchase of the product. Among the tests that have done are numerous perfectly controlled tests of serifed type v sans serif. In these controlled split run tests, the serif faces ALWAYS pulled more orders than the exact same words in sans serif. Always. Not just in the USA but in Britain and Europe as well, despite the evidence-free popularity of sans serif in those places. The obvious conclusion, proven over many millions of copies, is that serifed faces are more readable than sans. This conclusion was so well-documented repeatedly, that almost no text-heavy mailorder ads, or any ads which measure results, are printed in sans serif. Indeed, a text-heavy ad in a sans text is the mark of an incompetent.

Is it surprising that legalese, designed to be hard to read, is invariably sans serif?

The superiority of serifed text faces has been so well-proven in print applications for over a century that someone who argues otherwise is either an incompetent or a liar.

This answer needs citations. Alas, just because a direct marketing campaign returns particular results, it doesn't necessarily have any correlation to the actual readability of the typefaces. In other words, it's not an obvious conclusion. It's an arbitrary conclusion (again, unless the detailed data actually measured readability).
–
DA01May 16 '14 at 1:11

"well documented", "numerous perfectly controlled tests"... and not a single link in your answer. How about you post the link an actual study or two?
–
SylverdragMay 22 '14 at 18:31

Two characteristics of fonts which are often but not always correlated are the use of variable-width strokes and the attachment of perpendicular endings to strokes. Most serif fonts use both; most sans-serif fonts use neither. Do you know of any studies that examined the issues separately? I'm personally rather partial to sans-fonts which, like Univers or (to a lesser extent) Lucida Sans Unicode, vary stroke width, but many common sanserif fonts use uniform stroke widths.
–
supercatJun 16 '14 at 19:05

Some thoughts,
In my view (pardon the pun), I think your article would have been easier to read, e.g. I could have speed read or "skimmed" it, much faster had it been in a serif font. Btw, Georgia, as I understand is "the" best screen serif font according to some, it is my choice for word processing in my workplace on LED screens (non-retina display).

As I looked at the paragraphs, each word appeared to be block-ish as does all caps and we all know why that is bad to use, the brain does know shapes of words, not just letter patterns mentioned above, and that is more difficult to discern with sanserif, at least with the font you have on this page. Perhaps wider spaces between lines would have helped.

The point about newer screens is somewhat ironic as this page is still quite narrow although most people now have wider, inexpensive LED screens with better resolution than the old tube models. The argument that sanserif fonts work better on screens would be a good one if we all used retina displays, but that will be a long way off in the workplace and many households.